Patent Literature 1: JP-B 4564437 discloses a medicine dispensing apparatus serving as a medicine packaging apparatus which packages medicine such as tablets and powders by one package using a medicine packaging sheet while printing patient's name, time and date for taking medicines, etc. on the medicine packaging sheet.
The medicine dispensing apparatus of the Patent Literature 1 uses a medicine packaging sheet roll as a supply source of a medicine packaging sheet for packaging the medicine. The medicine packaging sheet is overlapped with an ink ribbon at a location of a printing head, so that the printing head prints the patient's name, time and date of taking the medicines, etc. The printed medicine packaging sheet is then folded into two so that the folded sheet has its open end facing upward to catch one package amount of the medicine such as tablets and powders.
If the apparatus is capable of indicating an amount of medicine packaging sheet remaining in the medicine packaging sheet roll (a remaining amount of a rolled material), the user should be able to know how many more packages he/she will be able to make by using the remaining medicine packaging sheet, and therefore they can plan for a best way which will minimize wasted amount in the medicine packaging sheet.
The remaining amount of the medicine packaging sheet can be obtained by subtracting the length which has been used from the original length of the medicine packaging sheet roll. A problem here is that there are always personal differences among human operators in the amount when cutting the medicine packaging sheet roll at an end of the roll at the time of manufacture; in other words, the original length of the roll is not always the same. Also, there is always some differences between production lots. For these reasons, it is impossible to determine a precise remainder although it is possible to get an approximate length of the remainder. This is because the rolls are always made to have some extra length over a specified length to compensate for non-exact nature of the roll cutting operation.
A remaining amount of the medicine packaging sheet can also be obtained by another method: as the medicine packaging sheet is unwound, an amount of rotation of the medicine packaging sheet roll is monitored to determine the diameter of the medicine packaging sheet roll, and from this diameter and a thickness of the medicine packaging sheet, it is possible to calculate the remaining amount. A problem here, however, is that the thickness of the medicine packaging sheet which is required in this method is not a thickness of the sheet itself, but a thickness which includes layers of air between layers of medicine packaging sheet laminated in the form of a roll.
However, the layers of air can vary depending on many different factors such as a tension of sheet when manufacturing the medicine packaging sheet roll, so it is impossible to know an exact thickness with accurate thickness of the layers of air. For these reasons, it has been difficult to let the user know an exact number of packages he/she can make from the remaining amount of sheet.
In view of the above aforementioned situations, embodiments of the present invention provides a medicine packaging apparatus, a medicine packaging sheet remaining amount determination method, and a medicine packaging sheet roll, for accurately determining a remaining amount of medicine packaging sheet.